#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define rep(i, a, b) for (int i = (a); i <= (b); i++)
#define per(i, a, b) for (int i = (a); i >= (b); i--)
#define endl '\n'
const int N = 1005;

int n, x0;
struct Node {
  int x, y, v;
  bool operator<(Node o) { return x < o.x; }
} a[N];
int x[N], ysum, v[N], vsum[N], num;
ll dp[1005][1005][2];
ll cost(int l, int r, int pre, int now) {
  int v = vsum[n] - (vsum[r] - vsum[l - 1]);
  int t = abs(x[now] - x[pre]);
  return 1ll * v * t;
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n >> x0;
  rep(i, 1, n) cin >> a[i].x;
  rep(i, 1, n) cin >> a[i].y;
  rep(i, 1, n) cin >> a[i].v;
  a[++n] = Node{x0, 0, 0};
  sort(a + 1, a + n + 1);
  rep(i, 1, n) {
    if (i == 1 || a[i].x != a[i - 1].x) x[++num] = a[i].x;
    v[num] += a[i].v;
    ysum += a[i].y;
  }
  rep(i, 1, num) vsum[i] += vsum[i - 1] + v[i];
  n = num;
  int pos = lower_bound(x + 1, x + n + 1, x0) - x;
  memset(dp, 0x3f, sizeof(dp));
  dp[pos][pos][0] = dp[pos][pos][1] = 0;
  rep(len, 2, n) {
    int lmn = max(1, pos + 1 - len);
    int lmx = min(pos, n + 1 - len);
    rep(l, lmn, lmx) {
      int r = l + len - 1;
      dp[l][r][0] = min(dp[l + 1][r][0] + cost(l + 1, r, l + 1, l),
                        dp[l + 1][r][1] + cost(l + 1, r, r, l));
      dp[l][r][1] = min(dp[l][r - 1][0] + cost(l, r - 1, l, r),
                        dp[l][r - 1][1] + cost(l, r - 1, r - 1, r));
    }
  }
  double res = (ysum - min(dp[1][n][0], dp[1][n][1])) / 1000.0;
  cout << fixed << setprecision(3) << res;
  return 0;
}